Centrifugal fan and method of making the same



CENTRIFUGAL FAN AND METHOD OF MAKING THE $AM'E Filed July 28, L928INVENTOR.

A 0 B. REP; 0645. q-

Ag BY Z5 Z/ ATTORNEY Patented May 13, 1930 PATENT OFFICE,

DANIEL B. REPLOGLE, OF BERKELEY, CALIFORNIA CENTRIFUGAL FAN AND METHODDIE MAKING THE SAME Application filed July 28, 1928. Serial No. 296,074.

The invention relates to centrifugal fans of the unshrouded type, and tothe method of making the same. Fans made in accordance with thisinvention may be used for various purposes, but are particularlyintended for use with suction cleaners and like devices, in which a "cryhigh speed of rotation is employed, running often as high as 20,000revolutions per minute. In devices of this charaeter it is essentialthat the fan be balanced dynamically as Well as statically, and for thisreason the shrouded type of fan has been found unsuitable as it ispractically impossible to maintain the dynamic balance in a fan of theshrouded type, besides shrouds furnish unnecessary air resistance.

Heretofore it has been customary in making centrifugal fans of theunshrouded type to secure the blades to a solid hub by means of screws,but with such method of fastening there is danger of the screws beingjarred loose during operation of the fan. Attempts have also been madeto weld the blades to a central hub of substantially greater thicknessthan the blades, but this has proved impractical owing to the unevenheating of the heavy metal of the hub and the thin metal of which theblades are composed. Centrifugal fans are also made by casting, but thedisadvantage of this method of manufacture lies in the fact that theblades of cast metal fans are often found to be of non-uniform densityor thickness and this defect destroys the dynamic balance of the fan.

The object of my invention is, therefore, to provide a non-shroudedcentrifugal fan of rigid construction, in which the parts are evenlybalanced both statically and dynamically and in which there is notendency for I the blades to workloose during the rotation of the fan. Afurther object of the invention is to provide a simple and inexpensivemethod of making and securing together the parts of i' the fan.

Broadly stated the method consists in the attachment by spot welding ofa plurality of vanes to a central open tube or like hollow member, theninserting a hub within the hollow member and securing the hub in place.

The invention may be more readily understood by reference to theaccompanying drawings in which Fig. 1 is a plan view of the fan, showingthe vanes, central tube and hub, and indicating the spot weldingattachment of the vanes to the central tube.

Fig. 2 is a vertical sectional view on the line 22 of Fig. 1, the vanes.being shown in elevation.

Fig. 3 is a detail fragmentary view showing a different form of vanefrom that disclosed in Fig. 2. a

Fig. at is a perspective view showing the vanes attached to the centraltube, but the hub not yet in place.

Fig. 5 is a plan view of the central tube.

Fig. 6 is an elevation of the central tube.

Fig. 7 is an elevation showing the hub which is to be secured within thecentral tube.

Fig. 8 is a plan View of a modification showing the hub assembled withina thimble-' shaped hollow hexagonal blade supporting member, the bladesnot being shown.

Fig. 9 is a'central vertical section on line 9-9 of Fig. 8.

Referring to the embodiment of the invention disclosed in Figs. 1 7, andparticularly to Figs. 5 and 6,-the fan includes a central hollow fiatsided tube l0,'preferably hexagonal in shape, which may be formed bysuitably bending a single sheet of. metal about av mandrel. The metalused is of material which lends itself readily to spot welding, and ispreferably sheet steel. Notches 11 are preferably formed betweenadjacent sides of the hexagonal tube, thereby forming tabs, lips, orflanges 12 at the ends of the tube which serve to bind the tube to asolid hub to be inserted after the vanes have been secured to the tube.

The vanes or blades 13 of the fan are preferably made up in. pairs orunits, with a flat connecting base member 14 between the divergingvanes. These vane units are composed of sheet metal of substantially thesame thickness as the central tube 10. For a sixbladed fan three ofthese units are employed. In addition to the blade units a plurality ofshort supplemental units are employed having a contour similar to thatof the blade units, these units each comprising wing members 15 and abase member 16. The blade units and the supplemental units are Securedto the central tubular member 10 by spot welding, the blade units andthe supplemental units being alternately arranged about the central tubewith the base members 14 and 16 in contact-with the sides 10 of thetube.

The welding is accomplished by inserting in the tube an electrode (notshown) conforming in shape to the interior of the tube, and pressinganother electrode against one of the' base members 14 or 16 therebyproducing a spot weld 17. -In this manner each of the blade unitsandsupplemental units is secured to the central tube. The adjacent sides13 and 15 of the respective blade and supplemental units may be spotwelded to each other as at 18, thus firmly and rigidly holding the partsof the fan in assembled position; The welding may be controlled so as tobe substantially uniform in character due to the thinness and uniformityof the parts to be welded together.

In order to complete the fan it is only necessary to apply a central hubmember by means of which the fan may be rotated on a suitable shaft. Ahub suitable for this purpose is shown in Fig. 7 -and comprises ahexagonal body member 19 conforming in size and shape to the interior ofthe tube 10. At the upper and lower portions of the hub the material iscut away as at 20 and 21, the depth of the cuts being the same as thethickness of the metal of which the tube 10 is composed. The top of thehub may be rounded as at 22, and the interior is hollowed out as at23'for the reception of a screw or the like (not shown) to connect tothe shaft of the fan motor (not shown).

The hub is fitted within the central tube a 10 and is secured in placeby means of the blade units, each consisting of a single blade and abase, may be employed in place of the three blade units each carryingtwo blades and a base. Also it is obvious that the number of sides ofthe central tube, and the number of blades may be varied as desired.

An' alternative form of the hollow central blade supporting member isshown in Figs. 8 and 9. According to this modification a hexagonalthimble 26 is stamped out of a sheet of metal, leaving a flange 27surrounding thebase of the thimble, and with a plurality of small tabsor lips 28 formed integral with the thimble and adapted to be bent overthe cut away portion 21 of the hub 19 to hold the hub in place, in thesame manner as the flanges 12 of the hollow tube 10.

Obviously other modifications may be resorted to without departing fromthe spirit of the invention.

What I claim as new and desire to secure by Letters Patent is 1. Themethod of making a centrifugal fan which consists in spot welding to acentral hollow metal member a plurality of blades of substantially thesame thickness as the central member, then inserting a hub within thehollow member and securing the hollow member and hub together.

2. In the method set forth in claim 1, the step which consists in spotwelding a plurality of supplemental reinforcing units to the centralhollow member and to adjacent blades.

3. A centrifugal fan comprising a hollow metal member, a plurality ofradial blade units having base portions welded to the central hollowmember and a central hub secured within the hollow member.

4, A centrifugal fan comprising a hollow flat sided metal member, aplurality of blade units each including a radial blade and a base bentat an angle thereto, the bases of the blade units being welded toalternate sides of the central hollow member, a plurality ofsupplemental reinforcing units conforming in shape to the blade units,each having a base of the same size as the bases of the blade units, buthaving shorter vanes, the bases of said supplemental units being weldedto the central tube intermediate the blade units and the vanes of thesupplemental units being welded to the blades of the blade units.

In testimony whereof I aflix my signature.

DANIEL B. REPLOGLE.

CERTIFICATE or CORRECTION.

Patent No. 1,758,062; 7 Granted May 13, 1930, to

DANIEL B. REPLOGLE.

It is hereby certified that the above numbered patent was erroneouslyissued to the inventor said "Replogle", as owner of said invention,whereas said patent should have been issued to "The Commerce GuardianTrust & Savings Bank, Trustee,

of Toledo, Ohio", as assignee of the entire interest in said invention,as shown by the records of assignments in this office; and that the saidLetters Patent should be read with this correction therein that the samemay conform to the record of the case in the Patent Office.

" Signed and sealed this 29th day of July, A. D. 1930.

V Wm. A. Kinnan, (Seal) Acting Commissioner of Patents.

